A lot of times i've spent a lot of energy trying to analyze the girls IOIs.
I spotted two neat little thoughts told by Steve 5.0 Point (Lovesystems):

1. (IOI) Green lights vs red lights
The idea is to not spot the green lights but rather consider the lack of a red light: "The girl is still standing there.", "The girl didn't turn her back on you", "The girl didn't avoid your question" etc.
This simplifies what youre observing and trying to spot in her - which also suits your mindset as you are the goal, not her. (of course she is into you.. She's still here.. Rock on dude)

2. The Gay Bar (for heterosexuals, disabling the thought: "Is she really into me?")
Imagine you, talking to your target. How does the target react? Is she touching you? Perhaps she laughs for rapport or any other IOI.
Now in the same situation, imagine you being the girl - but in a gay bar, as yourself. Would you touch another guy like that or laugh like that at that time etc if you were just mingling and not flirting? Probably not
This is also a great way to simplify the needs for observing which frees your energy for other stuff.

One of the useful points in these two strategies is to overcome/restrain your reaction to her and at the same time; your own inner-game. These thoughts could calm you in the situation and benefit your ability to restrain, mentally and immidiately.

Hope this is useful for some of you.
.. Good times, good times